Winona Ryder, Walking Dead favorite Jon Bernthal and Alfred Molina have joined the ranks of the six-hour entry, The Hollywood Reporter has learned.

Based on the nonfiction book by Lisa Belkin, Show Me a Hero is set in an America generations removed from the greatest civil rights struggles of the 1960s. It centers on Nick Wasicsko (Star Wars: Episode VII's Oscar Isaac), the young mayor of a midsize American city who is faced with a federal court order that says he must build a small number of low-income housing units in the white neighborhoods of his town. His attempt to do so tears the whole city apart, paralyzes the entire municipal government and, ultimately, destroys the mayor and his political future. Catherine Keener stars as Mary Dorman, an East Yonkers homeowner who comes to a remarkable realization during the battle over where to build low-income housing.

Ryder will portray Vinni Restiano, the Yonkers councilwoman and confidante to Wasicsko who lost her seat after her housing vote, only to stage a comeback four years later and wins as City Council president. The role marks Ryder's largest TV commitment to date after guest turns on Friends, Drunk History and The Simpsons. On the big screen, her credits include The Iceman, Black Swan, Girl, Interrupted and Edward Scissorhands, among others. She's repped by Gersh, Anonymous Content and Hirsch Wallerstein. Ryder recently wrapped Experimenter, opposite Peter Sarsgaard.

Molina is set as councilman Henry J. "Hank" Spallone, a tough-talking former NYPD detective from the Bronx who became the demagogic voice of the housing opponents. Repped by WME and Hyler Management, his credits include El Rey Network's Matador, The Normal Heart, Monday Mornings and features Chocolat, Raiders of the Lost Ark and Spider-Man 2.

Bernthal will play Michael H. Sussman, a hard-driving Harvard-trained lawyer who represented the NAACP when it joined the government’s anti-segregation case against Yonkers. Bernthal's breakout role was on AMC's The Walking Dead. He later reteamed with former Walking Dead showrunner Frank Darabont for TNT's short-lived drama Mob Cityand most recently had a role in The Wolf of Wall Street and next appears in Fury. He's repped by WME and the Burstein Co.

The trio joins a cast that also includes James Belushi, Terry Kinneyand Michael Stahl-David. Simon and William F. Zorzi will pen the script and executive produce alongside Nina Noble, Gail Mutrux and Paul Haggis, who will direct via The Wire creator's A Blown Deadline banner. HBO greenlit the mini on July 30.